title: Differential arsenic mobilization from As-bearing ferrihydrite by iron-respiring Shewanella strains with different arsenic-reducing activities.
abstract: Arsenic immobilization and release in the environment is significantly influenced by bacterial oxidation and reduction of arsenic and arsenic-bearing minerals. In this study, we tested three iron-reducing bacteria, Shewanella oneidensis MR-1, Shewanella sp. HN-41, and Shewanella putrefaciens 200, which have diverse arsenate-reducing activities with regard to reduction of an As-bearing ferrihydrite slurry. In the cultures of S. oneidensis MR-1 and Shewanella sp. HN-41, which are not capable of respiratory reduction of As(V) to As(III), arsenic was maintained predominantly in its pentavalent form, existing in particulate poorly crystalline As-bearing ferrihydrite and formed small quantities of a stable ferrous arsenate [Fe3(AsO4)2] precipitate. However, in the culture of the As(V) reducer, S. putrefaciens 200, As(V) was reduced to As(III) and a small fraction of As-bearing ferrihydrite was transformed into ribbon-shaped siderite that subsequently re-released arsenic into the liquid phase. Our results indicated that release of arsenic and formation of diverse secondary nanoscale Fe-As minerals are specifically closely related to the arsenic-reducing abilities of different bacteria. Therefore, bacterial arsenic reduction appears to significantly influence As mobilization in soils, minerals, and other Fe-rich environments.
authors.affiliation: School of Environmental Science and Engineering, Gwangju Institute of Science and Technology , Gwangju 500-712, Republic of Korea.
authors.forename: Shenghua
authors.initials: S
authors.lastname: Jiang
authors.forename: Ji-Hoon
authors.initials: JH
authors.lastname: Lee
authors.forename: Donghun
authors.initials: D
authors.lastname: Kim
authors.forename: Robert A
authors.initials: RA
authors.lastname: Kanaly
authors.forename: Min-Gyu
authors.initials: MG
authors.lastname: Kim
authors.forename: Hor-Gil
authors.initials: HG
authors.lastname: Hur
mesh_terms: D001151:Arsenic / Q000378:metabolism*; D001673:Biodegradation, Environmental; D005290:Ferric Compounds / Q000378:metabolism*; D007501:Iron / Q000378:metabolism*; D046529:Microscopy, Electron, Transmission; D010084:Oxidation-Reduction; D020592:Shewanella / Q000378:metabolism*; D056928:X-Ray Absorption Spectroscopy
chemical_list: D005290:Ferric Compounds; C092844:ferric oxyhydroxide; D007501:Iron; D001151:Arsenic